In the digital communication network according to CCITT Recommendations G. 709, the digital signals to be transmitted are inserted into special data function blocks called containers. These are extended by adding additional information (POH) to form virtual containers VC-n and can in turn be combined again to form "tributary units" TU-n or higher-order virtual containers and administrative units, and can be transmitted, inserted into a synchronous transport module STM-1, on the 155-Mbit/s level (or a higher level). The administrative or tributary units are switched through via switching networks (cross-connectors) in the form of special data blocks (cross-connect data blocks). In addition to the meaningful information (payload), data for switching path addresses, processor information, error control, alarm signals, etc. are also to be transmitted. The pulse frame of the STM-1 signal does not have the additional transmission capacity required for these data.
A method for switching through multiplexed signals via cross-connectors is known from European Patent Application EP-A3-0 407 851 (corresponding to U.S. Pat. No. 5,123,010. However, the pulse frame used therein permits only the transmission of a small amount of special information.